They have trouble making decisions. They would rather hike in the Himalayas than climb a corporate ladder. They have few heroes, no anthems, no style to call their own. They crave entertainment, but their attention span is as short as one zap of a TV dial. They hate yuppies, hippies and druggies. They postpone marriage because they dread divorce. They sneer at Range Rovers, Rolexes and red suspenders. What they hold dear are family life, local activism, national parks, penny loafers and mountain bikes. They possess only a hazy sense of their own identity but a monumental preoccupation with all the problems the preceding generation will leave for them to fix.

This is the twentysomething generation, those 48 million young Americans ages 18 through 29 who fall between the famous baby boomers and the boomlet of children the baby boomers are producing. Since today's young adults were born during a period when the U.S. birthrate decreased to half the level of its postwar peak, in the wake of the great baby boom, they are sometimes called the baby busters. By whatever name, so far they are an unsung generation, hardly recognized as a social force or even noticed much at all. "I envision ourselves as a lurking generation, waiting in the shadows, quietly figuring out our plan," says Rebecca Winke, 19, of Madison, Wis. "Maybe that's why nobody notices us."

But here they come: freshly minted grownups. And anyone who expected they would echo the boomers who came before, bringing more of the same attitude, should brace for a surprise. This crowd is profoundly different from -- even contrary to -- the group that came of age in the 1960s and that celebrates itself each week on The Wonder Years and thirtysomething. By and large, the 18-to-29 group scornfully rejects the habits and values of the baby boomers, viewing that group as self-centered, fickle and impractical.

While the baby boomers had a placid childhood in the 1950s, which helped inspire them to start their revolution, today's twentysomething generation grew up in a time of drugs, divorce and economic strain. They virtually reared themselves. TV provided the surrogate parenting, and Ronald Reagan starred as the real-life Mister Rogers, dispensing reassurance during their troubled adolescence. Reagan's message: problems can be shelved until later. A prime characteristic of today's young adults is their desire to avoid risk, pain and rapid change. They feel paralyzed by the social problems they see as their inheritance: racial strife, homelessness, AIDS, fractured families and federal deficits. "It is almost our role to be passive," says Peter Smith, 23, a newspaper reporter in Ventura, Calif. "College was a time of mass apathy, with pockets of change. Many global events seem out of our control."